linux-kernel - Re: [sched next] overflowed cpu time for kernel threads in /proc/PID/stat

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Date:	Tue, 3 Sep 2013 20:32:29 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:	Stanislaw Gruszka <sgruszka@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org
Subject: Re: [sched next] overflowed cpu time for kernel threads in
 /proc/PID/stat


* Sergey Senozhatsky <sergey.senozhatsky@...il.com> wrote:

> On (09/03/13 10:43), Stanislaw Gruszka wrote:
> > Ok, I see now, utime is 0 . This seems to be problem with dynamic ticks
> > as you told that your application is kernel compilation, so we utilize
> > lot of cpu time in user-space.
> > 
> > Anyway we should handle utime == 0 situation on scaling code. We work
> > well when rtime & stime are not big (variables and results fit in
> > 32 bit), otherwise we have that stime bigger than rtime problem. Let's
> > try to handle the problem by below patch. Sergey, does it work for you ?
> 
> checked on -current and -next -- works fine, good job.
> 
> here are my:
> Reported-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> Tested-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>

Cool and thanks for the patient reporting and testing!

Stanislaw, mind sending a changelogged, signed off patch with Sergey's 
tags included? It also warrants a -stable backport tag I think.

Thanks,

	Ingo
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